Implantable distraction device

ABSTRACT

The present invention relates to a monitoring method for generating a distraction indicator, including: receiving data from an implantable bone distraction device, corresponding to a mechanical vibration response of a medium comprising the implantable bone distraction device, as measured by at least one vibration sensor; computing from the received data a distraction indicator through at least the steps of: determining at least one vibration pattern of said medium from the vibration response measured by the at least one vibration sensor; analyzing the evolution of a first value of the at least one vibration pattern of said medium determined from the measured vibration response during a first period; and generating a distraction indicator as a function of the first value.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a divisional of U.S. patent application Ser.No. 16/768,670, filed May 30, 2020, which is a 371 of PCT/EP2018/083216,filed Nov. 30, 2018, which claims priority to both: U.S. patentapplication Ser. No. 15/947,495 (now U.S. Pat. No. 11,376,043) filed onApr. 6, 2018, and EP Patent Application (FR) 17306662.2 filed on Nov.30, 2017. Each of the foregoing are hereby incorporated by reference asif set forth in their entireties.

TECHNICAL FIELD

The present invention pertains to the field of implantable bonedistraction devices.

BACKGROUND

Distraction osteogenesis is a technique which has been used to grow newbone in patients with a variety of defects. For example, limblengthening is a technique in which the length of a bone (for example afemur or a tibia) may be increased. By creating a corticotomy, orosteotomy, in the bone, which is a cut through the bone, the tworesulting bone sections may be moved apart at a particular rate, such asone millimeter per day, allowing new bone to regenerate between the twosections as they move apart. This technique of limb lengthening is usedin cases where one limb is longer than the other, such as in a patientwhose prior bone break did not heal correctly, or in a patient whosegrowth plate was diseased or damaged prior to maturity. In somepatients, stature lengthening is desired, and is achieved by lengtheningboth femurs and/or both tibia to increase the patient's height.

The prior art includes the U.S. Pat. No. 5,364,396 which discloses animplantable bone distraction device and a method associated. Thisimplantable bone device comprises two blocks, each fixed to a separatedbone section and linked together to a rotatable drive rod and a driverod actuator. The actuation of the drive rod actuator leads to arotation of the rotatable drive rod which moves apart the two blocks.

However, the speed or the rate of the move of the two resulting bonesections is critical. Indeed, the osteotomy results in a gap between thetwo separated bone sections. The callus is used herein to describe theheterogeneous tissue involved in the intermediate stage of boneformation or bone healing in the gap between the two separated bonesections.

If the rate is too fast, the callus may be split and no bone healingprocess will occur. If the rate is too slow, the bone healing processmay be too developed to move apart the two bone sections and a newosteotomy will be needed.

Therefore, the present invention is intended to provide an implantablebone distraction device and a medical monitoring device to continuouslyor semi-continuously monitor and identify the bone healing processbetween separated bone sections.

SUMMARY

This invention thus relates, in a first aspect, to an implantable bonedistraction device for distracting osteotomically separated bonesections, the implantable distraction device comprising: a first blockfor implantation and attachment to a first bone section, the first blockdefining a first chamber bore; a second block for implantation andattachment to a second bone section separated from the first bonesection by an osteotomy, the second block defining a second chamberbore; an actuator including means for adjusting the space between thefirst block and the second block when activated, enabling distractionbetween the first bone section and the second bone section; and at leastone vibration sensor arranged in an area located between the first blockand the second block and oriented in order to measure a vibrationresponse of a medium comprising the implantable bone distraction device.

In one embodiment, the implantable distraction device comprises a driverod having a first end received in the first chamber bore and a secondend, opposite from the first end, received in the second chamber bore;the drive rod being able to adjust the space between the first block andthe second block.

In one embodiment, the at least one vibration sensor is oriented inorder to measure a vibration response of a medium comprising theimplantable bone distraction device in the direction of the drive rod.

An advantage of the device of the invention is its ability to measurecriteria of the formation of the callus in order to give an indicator toan operator or a doctor, the indicator being representative of the stateof the fusion. The arrangement of the sensor contributes to generate arelevant indicator.

According to one embodiment, the at least one vibration sensor is apiezoelectric element or an accelerometer. According to one embodiment,the at least one vibration sensor is arranged to measure a vibrationresponse corresponding to mechanical vibrations.

According to one embodiment, the medium further comprises the firstseparated bone section and the second separated bone section.

According to one embodiment, the at least one vibration sensor isarranged to measure an evolution of the vibration response of themedium, allowing monitoring of the evolution of the bone fusion process.

According to one embodiment, the implantable bone distraction devicecomprises a drive rod actuator cooperating with the drive rod to adjustthe space between the first block and the second block when activated,enabling distraction between the first bone section and the second bonesection.

According to one embodiment, the first chamber bore is a drive chamberbore; the second chamber bore is a threaded bore; the second end of thedrive rod is a threaded end threadably received in the threaded bore ofthe second block; and the actuator cooperates with the drive rod torotate the drive rod; the drive rod being able to adjust the spacebetween the first block and the second block by rotation.

According to one embodiment, the implantable bone distraction devicecomprises at least one vibration sensor oriented so as to measure avibration response of the medium in the direction of the drive rod.

According to one embodiment, the implantable bone distraction devicecomprises at least two vibration sensors, including a first vibrationsensor for measuring a vibration response of the medium in thelongitudinal direction of the drive rod and a second vibration sensorfor measuring a vibration response of the medium in a directionperpendicular to the longitudinal direction of the drive rod.

According to one embodiment, the implantable bone distraction devicefurther comprises a wireless interface for transmitting data measured bythe at least one vibration sensor.

According to one embodiment, the implantable bone distraction devicedoes not comprise a vibration excitation transducer.

According to one embodiment, the implantable bone distraction devicefurther comprises a memory to store data measured by the at least onevibration sensor.

In a second aspect, the present invention relates to a medicalmonitoring device comprising: a receiver for receiving data from animplantable bone distraction device, corresponding to a mechanicalvibration response of a medium comprising the implantable bonedistraction device, as measured by at least one vibration sensor; acalculator for computing, from the data received by the receiver, adistraction indicator through at least the steps of: determining atleast one vibration pattern of the medium from the vibration responsemeasured by the at least one vibration sensor; analyzing the evolutionof a first value of the at least one vibration pattern of the medium,determined from the measured vibration response measured by the at leastone vibration sensor during a first period; and generating a distractionindicator as a function of the first value.

According to one embodiment, the step of generating a distractionindicator is executed when the first value exceeds a predefinedthreshold.

According to one embodiment, the medical monitoring device comprises: areceiver for receiving data from an implantable bone distraction device,corresponding to a mechanical vibration response of a medium comprisingthe implantable bone distraction device, as measured by at least onevibration sensor; a calculator for computing, from the data received bythe receiver, a distraction indicator through at least the steps of:determining at least one vibration pattern of the medium from thevibration response measured by the at least one vibration sensor;analyzing the evolution of a first value of the at least one vibrationpattern of the medium, determined from the measured vibration responsemeasured by the at least one vibration sensor during a first period;analyzing the evolution of a second value of the at least one vibrationpattern of the medium, determined from the measured vibration responsemeasured by the at least one vibration sensor during a second period;performing a comparison between the first value and the second value;and generating a distraction indicator as a function of the comparison.

According to one embodiment, the step of generating a distractionindicator is executed when the comparison exceeds a predefinedthreshold.

According to one embodiment, the at least one vibration pattern is aresonant frequency of the medium.

According to one embodiment, the at least one vibration pattern is afunction of the damping factor.

The processing steps of the signal contribute to generate a relevantindicator, for example by determining a relevant pattern and achievingcorrelation functions with some relevant values and for instance bycomparing the different values of the pattern in a predefined duration.

According to one embodiment, the medical monitoring device furthercomprises a transmitter for transmitting, to the implantable bonedistraction device, instructions for providing a distraction when adistraction indicator is generated by the calculator.

According to one embodiment, the mechanical vibration response of themedium measured by the at least one vibration sensor allows monitoringof the evolution of the bone fusion process.

In a third aspect, the present invention relates to a medical systemcomprising an implantable bone distraction device according to the firstaspect of the present invention and a medical monitoring deviceaccording to the second aspect of the present invention, wherein themedical system comprises an interface which activates the transmissionof vibration data from the implantable bone distraction device, to bereceived by the medical monitoring device, wherein the vibration datacorrespond to a mechanical vibration response of a medium comprising theimplantable bone distraction device, as measured by at least onevibration sensor.

The implantable bone distraction device and the medical monitoringdevice cooperate to produce a combined technical effect so as to improvethe indicator related to the bone fusion process. The specificarrangement of the bone distraction device, and in particular of the atleast one vibration sensor, and the steps performed by the calculatorallowing the extraction of the at least one vibration pattern accordingto the invention, when used in combination, allow the medical system tobe particularly efficient.

According to one embodiment, the implantable bone distraction devicecomprises actuation means for actuating the actuator, and the medicalmonitoring device comprises a transmitter connected to the actuationmeans for automatically activating the actuator when a distractionindicator is generated.

In a fourth aspect, the present invention relates to a method forgenerating a distraction indicator, comprising: receiving data from animplantable bone distraction device, corresponding to a mechanicalvibration response of a medium comprising the implantable bonedistraction device, as measured by at least one vibration sensor;computing, from the received data, a distraction indicator through atleast the steps of: determining at least one vibration pattern of themedium from the vibration response measured by the at least onevibration sensor; analyzing the evolution of a first value of the atleast one vibration pattern of the medium, determined from the measuredvibration response measured by the at least one vibration sensor duringa first period; and generating a distraction indicator as a function ofthe first value.

According to one embodiment, the step of generating a distractionindicator is executed when the first value exceeds a predefinedthreshold.

According to one embodiment, the method for generating a distractionindicator comprises: receiving data from an implantable bone distractiondevice, corresponding to a mechanical vibration response of a mediumcomprising the implantable bone distraction device, as measured by atleast one vibration sensor; computing, from the received data, adistraction indicator through at least the steps of: determining atleast one vibration pattern of the medium from the vibration responsemeasured by the at least one vibration sensor; analyzing the evolutionof a first value of the at least one vibration pattern of the medium,determined from the measured vibration response measured by the at leastone vibration sensor during a first period; analyzing the evolution of asecond value of the at least one vibration pattern of the medium,determined from the measured vibration response measured by the at leastone vibration sensor during a second period; performing a comparisonbetween the first value and the second value; and generating adistraction indicator as a function of the comparison.

According to one embodiment, the step of generating a distractionindicator is executed when the comparison exceeds a predefinedthreshold.

According to one embodiment, the method further comprises a step oftransmitting, to the implantable bone distraction device, instructionsfor providing a distraction when a distraction indicator is generated.

According to one embodiment, the method further comprises a step ofadjusting the space between two separated bone sections by increasing orreducing the space of a predetermined pitch when a distraction indicatoris generated.

According to one embodiment, a monitoring method for generating adistraction indicator includes: receiving data from an implantable bonedistraction device, corresponding to a mechanical vibration response ofa medium comprising the implantable bone distraction device, as measuredby at least one vibration sensor; computing from the received data adistraction indicator through at least the steps of: determining atleast one vibration pattern of said medium from the vibration responsemeasured by the at least one vibration sensor; analyzing the evolutionof a first value of the at least one vibration pattern of said mediumdetermined from the measured vibration response during a first period;and generating a distraction indicator as a function of the first value.

In some cases, computing the distraction indicator from the receiveddata comprises: determining at least one vibration pattern of saidmedium from the vibration response measured by the at least onevibration sensor; analyzing the evolution of a first value of the atleast one vibration pattern of said medium determined from the measuredvibration response during a first period; analyzing the evolution of asecond value of the at least one vibration pattern of said mediumdetermined from the measured vibration response during a second period;performing a comparison between the first value and the second value;and generating a distraction indicator as a function of said comparison.

In certain cases, generating the distraction indicator is performed whena comparison between the first value and the second value exceeds apredefined threshold.

In some cases, the predefined threshold ranges from approximately 1percent to approximately 7 percent of the first value.

In some cases, the predefined threshold ranges from approximately 0.5percent to approximately 10 percent of the first value.

In some cases, the predefined threshold ranges from approximately 0.5percent to approximately 20 percent of the first value.

In some cases, the at least one vibration sensor is implanted in apatient.

In some cases, the method further includes calculating a distractionindicator from the received vibration data as a function of an evolutionof the vibration data over time, wherein the evolution of the vibrationdata is an indicator of callus formation between the first bone sectionand the second bone section.

In some cases, the method further includes transmitting instructions tothe implantable bone distraction device for providing a distraction whenthe distraction indicator is generated.

In some cases, the method further includes adjusting a space between twoseparated bone sections by increasing the space when the distractionindicator is generated.

In some cases, the method further includes adjusting a space between twoseparated bone sections by reducing the space when the distractionindicator is generated.

In some cases, the implantable bone distraction device is configured tomeasure a vibration response of the medium at a frequency range of fromapproximately 20 Hertz (Hz) to approximately 10,000 Hz.

In some cases, the implantable bone distraction device is configured tomeasure a vibration response of the medium at a frequency range of fromapproximately 30 Hz to approximately 7,000 Hz.

In some cases, the implantable bone distraction device is configured tomeasure a vibration response of the medium at a frequency range of fromapproximately 40 Hz to approximately 5,000 Hz.

In some cases, determining the at least one vibration pattern of themedium is performed continuously or semi-continuously.

In some cases, when the first value of the vibration pattern isdetermined, the first value becomes the reference.

Definitions

In the present invention, the following terms have the followingmeanings:

“Block” refers to a part configured to be attached to a bone section.

“Resonant frequency” refers to the frequency at which the responseamplitude is a relative maximum.

“Peak” refers to a frequency or a narrow range of frequencies for whichthe response amplitude is a relative maximum.

“Vibration response” refers to an amplitude of a movement of an objector a system on its own until it returns to its resting state.

“Young's modulus” refers to the elastic modulus, measuring the stiffnessof a solid material.

“Vibration pattern” refers to a characteristic of a vibration data, thevibration pattern may be extracted through a vibration signal or avibration spectrum, or any other signal processing.

“Bone fusion process” refers to the process of formation of adistraction callus between two separated bone sections or boneregeneration between two bone sections.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of this specification, show certain aspects of the subject matterdisclosed herein and, together with the description, help explain someof the principles associated with the disclosed implementations. In thedrawings,

FIG. 1 is a front view of an implantable bone distraction deviceaccording to an embodiment mounted on two separated bone sections.

FIG. 2 is a front view of an implantable bone distraction deviceaccording to an embodiment mounted on two separated bone sections, thevibration sensor being arranged on one of the separated bone sections.

FIG. 3 is a side view of an implantable bone distraction deviceaccording to an embodiment mounted on two separated bone sections.

FIG. 4 is a side view of an implantable bone distraction deviceaccording to an embodiment integrating a wirelessly powered actuator,and two vibration sensors.

FIG. 5 is a side view of an implantable bone distraction deviceaccording to an embodiment integrating a wirelessly powered actuator,and one vibration sensor.

It is noted that the drawings of the subject matter are not necessarilyto scale. The drawings are intended to depict only typical aspects ofthe subject matter, and therefore, should not be considered as limitingthe scope of the disclosed subject matter. In the drawings, likenumbering represents like elements between the drawings.

DETAILED DESCRIPTION

The first aspect of the present invention relates to an implantable bonedistraction device for distracting osteotomically separated bonesections, comprising a vibration sensor to monitor the bone healingprocess between the two separated bone sections.

As illustrated in FIG. 1 , the implantable bone distraction device 1comprises a first block 3 for implantation and attachment to a firstbone section 2, the first block 3 defining a first chamber bore. Theimplantable bone distraction device 1 comprises a second block 3′ forimplantation and attachment to a second bone section 2′ separated fromthe first bone section 2 by an osteotomy, the second block 3′ defining asecond chamber bore. In one embodiment, the implantable bone distractiondevice 1 comprises a drive rod 5 having a first end received in thefirst chamber bore and a second end, opposite from the first end,received in the second chamber bore; the drive rod 5 being able toadjust the space between the first block 3 and the second block 3′.

The implantable bone distraction device 1 further comprises an actuatorto adjust the space between the first block 3 and the second block 3′when activated, enabling distraction between the first bone section 2and the second bone section 2′.

In one embodiment, the actuator is a drive rod actuator 4 cooperatingwith the drive rod 5 to adjust the space between the first block 3 andthe second block 3′ when activated, enabling distraction between thefirst bone section 2 and the second bone section 2′.

The implantable bone distraction device 1 further comprises at least onevibration sensor 6 arranged in an area located between the first block 3and the second block 3′ and oriented in order to measure a vibrationresponse of a medium comprising the implantable bone distraction device1. In one embodiment, the medium further comprises the first and secondbone sections 2, 2′. In one embodiment, the medium further comprises thecallus located in the gap between the two separated bone sections. Inone embodiment, the medium further comprises the environment of theimplantable bone distraction device. In one embodiment, the mediumfurther comprises surrounding tissues of the implantable bonedistraction device such as the adjacent bones, muscles, ligaments.

In one embodiment, the vibration sensor 6 is arranged, located andoriented to measure a vibration response which may evolve with theformation of the callus.

In one embodiment, the vibration sensor 6 is located as close aspossible to the callus. In one embodiment, the vibration sensor 6 islocated on the implantable bone distraction device 1. In one embodiment,the vibration sensor 6 is located on the first block 3 or on the secondblock 3′ as illustrated in FIG. 1 . In one embodiment, the vibrationsensor 6 is located on the drive rod 5 or on the drive rod actuator 4.In one embodiment, the vibration sensor is transversally aligned, alongthe longitudinal direction of the drive rod 5, with the first block 3 orwith the second block 3′ as illustrated in FIG. 5 . In anotherembodiment as illustrated in FIG. 2 , the vibration sensor 6 isconfigured to be located on the first bone section 2 or on the secondbone section 2′.

In one embodiment, the vibration sensor is oriented in order to measurea vibration response of a medium comprising the implantable bonedistraction device in the direction of the drive rod.

In one embodiment, the drive rod is a longitudinal element extendingalong a longitudinal direction in the axis of the first and secondblocks. In one embodiment, the vibration sensor 6 is oriented to measuremechanical vibrations in the longitudinal direction of the drive rod 5.In one embodiment, the vibration sensor is oriented to measuremechanical vibrations in a direction perpendicular to the longitudinaldirection of the drive rod.

According to one embodiment illustrated in FIG. 4 , the first block 3comprises a longitudinal groove and the second block 3′ is able to movealong the groove to increase the space between the first and secondblock, as it can be seen in FIG. 5 .

According to one embodiment, the implantable bone distraction device 1comprises at least two vibration sensors 6: a first vibration sensor formeasuring the mechanical vibrations in the longitudinal direction of thedrive rod 5 and a second vibration sensor for measuring the mechanicalvibrations in a direction perpendicular to the longitudinal direction ofthe drive rod 5. According to another embodiment, the implantable bonedistraction device 1 comprises at least three vibration sensors 6: afirst vibration sensor for measuring the mechanical vibrations in thelongitudinal direction of the drive rod 5 and a second and a thirdvibrations sensor for measuring the mechanical vibrations in the twoorthogonal directions to the longitudinal direction of the drive rod.

In one embodiment illustrated in FIG. 3 , the implantable bonedistraction device 1 comprises: a first block 3 for implantation andattachment to a first bone section 2, the first block 3 defining a drivechamber bore; a second block 3′ for implantation and attachment to asecond bone section 2′ separated from the first bone section 2 by anosteotomy, the second block 3′ defining a threaded bore; a rotatabledrive rod 5 having a first drive end received in the drive chamber boreand a second threaded end, opposite to the first drive end, received inthe threaded bore; and an actuator located in the drive chamber borecooperating with the first drive end to rotate the first drive end andto adjust the space between the first and second block when activated,enabling distraction between the first and second bone sections.

In one embodiment, the actuator is a drive rod actuator.

In one embodiment, the drive rod actuator includes a distraction screw.The distraction screw cooperates with the drive rod 5 to rotate thedrive rod so that the inherent depth to which the threaded distal end ofthe drive rod is threadably received within the threaded bore can beadjusted. This adjustment makes it possible to adjust the spacingbetween the first block and the second block, which enables distractionbetween the first and second bone sections. In this way, bone growththerebetween can be enhanced. In this embodiment, the operator, byscrewing the drive rod actuator 4, can control the space between thefirst block 3 and the second block 3′.

In one embodiment, the at least one vibration sensor 6 continuously orsemi-continuously records the vibration response of the medium during apredetermined time. According to one embodiment, the at least onevibration sensor 6 is arranged to measure a vibration responsecorresponding to mechanical vibrations. According to one embodiment, theat least one vibration sensor 6 is configured to measure a vibrationfrequency value and/or a vibration amplitude value of the medium.According to one embodiment, the at least one vibration sensor 6 isplaced on the first block, on the second block, on the drive rodactuator and/or on the rotatable drive rod.

According to one preferred embodiment, the at least one vibration sensoris a piezoelectric element. The piezoelectric vibration sensor, whenexposed to a mechanical stress or a deformation, is able to provide anelectric field. The current provided by the piezoelectric element is afunction of the intensity of the deformation (or stress). Apiezoelectric element is able to measure the amplitude and the frequencyof the vibrations.

According to one preferred embodiment, the at least one vibration sensor6 is an accelerometer element. The accelerometer is an electromechanicaldevice that may measure both static (gravity) and dynamic (motion orvibration) accelerations.

According to one embodiment, the signal generated by the at least onevibration sensor 6 makes it possible to obtain a frequency spectrum. Inone embodiment, the signal generated by the at least one vibrationsensor 11 is transformed by a Fourier transform or a wavelet transformto obtain a frequency spectrum.

Indeed, the vibration sensor 6 is able to create an electric charge inresponse to applied mechanical stress. When a vibration occurs, thevibration sensor measures the vibration response of the medium.

The advantage of this solution is due to the evolution of the callus.Indeed, the stiffness of the callus evolves with the bone fusionprocess. Furthermore, the evolution of the stiffness of the callus willmodify the vibration response of the medium. Then, the evolution of thebone fusion process can be monitored, thereby enabling the generation ofan information to an operator. In this way, the operator can control thespeed of the distraction between the first and second bone sections as afunction of the osteogenesis.

According to one embodiment, the at least one vibration sensor isconfigured to measure a vibration response of the medium at a frequencyranging of from 20 Hz to 10000 Hz, preferably from 30 Hz to 7000 Hz,more preferably from 40 Hz to 5000 Hz.

According to one embodiment, the implantable bone distraction device 1does not comprise a vibration excitation transducer. A vibrationexcitation transducer may increase the noise recorded by the vibrationsensor and needs more energy to be used. Indeed, mechanical waves arenaturally generated by the movement of the spinal column. According toone embodiment, the vibration sensor is also able to emit a vibration.

After the implantation of the implantable bone distraction device 1 onthe user body, a process of osteogenesis is expected between the twoseparated bone sections. The advancement of the bone fusion process isable to modify the stiffness of the medium comprising the implantablebone distraction device 1 and the separated bone sections 2, 2′ andthen, is able to modify the vibration response.

Because of the movement of the human body during a day, the implantablebone distraction device is continuously exposed to vibrations. Thesevibrations are associated to various frequencies.

By recording continuously or semi-continuously these frequencies withthe vibration sensor, the applicant found that, with enough time (fromseveral hours to a few days), a wide range of frequencies were recordedwhich can allow the medical device to analyze the vibration response ona wide range of frequencies.

In other words, the monitoring of the amplitudes of the vibrations andtheir frequencies, makes it possible to generate a frequency spectrum ofthe vibrations in the medium comprising the implantable bone distractiondevice.

In another embodiment, mechanical vibrations may be generated by adevice at the exterior of the human body.

In one embodiment, the implantable bone distraction device 1 furthercomprises means for transmitting data measured by the vibration sensorfrom the implantable bone distraction device 1 or from the vibrationsensor to an external device.

In one embodiment, the implantable bone distraction device 1 furthercomprises a wireless interface for transmitting the measurements.

In one embodiment, the implantable bone distraction device 1 furthercomprises means for storing the data measured by the at least onevibration sensor 6. The means for storing the measured data may be amemory, the memory being connected to the at least one vibration sensor6.

In one embodiment, the memory is connected to an interface (which may bewireless) for transmitting the measured data.

In one embodiment, the drive rod actuator 4 is cooperating with thedrive rod 5. This cooperation leads to an adjustment (increase ordecrease) of the space between the first and second blocks 3, 3′,enabling distraction between the first and second bone sections 2, 2′.

Indeed, the distraction process includes increasing the space betweenthe two bone sections when a bridge of bone fusion is achieved. Theactivation of the drive rod actuator leads to the rotation of therotatable drive rod and increases the space between the first and secondbone sections.

In one embodiment, the detection of a formation of a bridge of bonefusion between the two bone sections automatically activates theactuator to increase the space between the two bone sections.

In one embodiment, the implantable bone distraction device 1 comprisesactuation means for actuating the drive rod actuator 4. According to oneembodiment, the actuation means for actuating the drive rod actuator 4are connected to an external device. According to one embodiment, thedrive rod actuator 4 comprises an electric, pneumatic or hydraulic motorable to actuate the drive rod actuator 4.

In a preferred embodiment, the actuation means for actuating the driverod actuator 4 comprises a receiver. The receiver may be able to receivea signal from an external device, and to activate the drive rod actuator4.

According to a second aspect, the present invention relates to a medicalmonitoring device comprising a receiver and a calculator.

In one embodiment, the medical monitoring device comprises a receiverfor receiving data from an implantable bone distraction devicecorresponding to mechanical vibrations of the medium. In one embodiment,the medium comprises the implantable bone distraction device andoptionally further comprises the two separated bone sections and/or thecallus between the two separated bone sections.

In one embodiment, the medical monitoring device comprises a calculatorfor computing, from the received data, a distraction indicator.

In one embodiment, the distraction indicator is computed by thecalculator through at least the steps of: determining at least one firstvibration pattern of the medium from the vibration response measured bythe at least one sensor 6; analyzing the evolution of a first value ofat least one vibration pattern of the medium, determined from themeasured vibration response during a first period; and generating adistraction indicator when the first value exceeds a predefinedthreshold.

In one embodiment, the distraction indicator is computed by thecalculator through at least the steps of: determining at least one firstvibration pattern of the medium from the vibration response measured bythe at least one sensor 6; analyzing the evolution of a first value ofat least one vibration pattern of the medium, determined from themeasured vibration response during a first period; and defining thefirst value as a reference value; overtime, analyzing the evolution ofat least one second value of the at least one vibration pattern of themedium, determined from the measured vibration response during a secondperiod; comparing the at least one second value and the reference firstvalue; and generating a distraction indicator when the comparisonexceeds a predefined threshold.

In one embodiment, the evolution of values is determined as a functionof a comparison between the first value and the at least one secondvalue.

In one embodiment, the predefined threshold is manually provided to thecalculator through a user interface. According to one embodiment, thepredetermined threshold is ranging from 1% to 7% of the first value,preferably ranging from 0.5% to 10% of the first value or ranging from0.5% to 20% of the first value.

In one embodiment, the at least one vibration pattern is continuously orsemi-continuously determined. In one embodiment, when a first value ofthe vibration pattern is determined, the first value becomes thereference.

When a second value of the vibration pattern is determined, thecalculator compares the new second value to the reference. In oneembodiment, the comparison is a difference or a function comprising adifference. In one embodiment, when the difference exceeds apredetermined threshold, the calculator generates a distractionindicator.

According to one embodiment, the step of comparing the first value andthe at least one second value comprises the steps of calculating thedifference between the first value and the second value, and comparingthe difference to a predetermined threshold.

According to one embodiment, the predetermined threshold is ranging from1% to 7% of the first value, preferably ranging from 0.5% to 10% of thefirst value or ranging from 0.5% to 20% of the first value.

In one embodiment, the calculator repeatedly executes the step ofdetermining a second value of the vibration pattern and comparing thesecond value to the reference until the comparison exceeds thepredefined threshold.

In one embodiment, the distraction indicator indicates a structuralchange of the physical properties of the callus between the first periodand a second period during which the second value is determined.

In one embodiment, the generated distraction indicator reflects astructural change of the medium comprising the callus between twoperiods of time. In one embodiment, the generated distraction indicatorreflects a structural change of the medium comprising the callus betweena first period of reference and a second period. In one embodiment, thefirst period of reference corresponds to the period of the lastactivation of the drive rod actuator.

In one embodiment, the distraction indicator reflects a beginning of asolidification of the callus.

The operator can then actuate the implantable bone distraction device toadjust the space between the separated bone sections allowingdistraction. In one embodiment, the method is executed from thebeginning after an adjustment of the space between the separated bonesections. In one embodiment, the first value of the vibration pattern orthe reference is the first value of the vibration pattern determinedafter an adjustment of the space between the separated bone sections.

According to one embodiment, the monitoring device further comprises animpedance meter, and/or a user interface such as a display. According toone embodiment, the interface is required to allow the user to providemeasurement parameters and to display the at least one generateddistraction indicator.

In one embodiment, the calculator comprises a memory. In one embodiment,the memory comprises a value of a predefined threshold. In oneembodiment, the calculator is able to store the determined values of thevibration pattern in its memory. According to one embodiment, themedical monitoring device comprises a memory unit able to store themeasured data received from the implantable bone distraction device.

In one embodiment, the computation step comprises the steps of:determining at least one second value of the at least one vibrationpattern of the medium from the measured vibration response; comparingthe first value and the at least one second value; and determining anevolution as a function of the comparison.

In one embodiment, the present invention uses the measure of thevibration response to provide information on the bone fusion process.The measurement of the vibration leads to the observation of somevibration patterns.

In one embodiment, the vibration pattern is the resonant frequency.Generally, when a solid material is exposed to vibrations, the responseof the material to the vibrations is substantially the same. However,there are specific frequencies for which the response is relevantlyhigher than for the other frequencies. These specific frequencies arecalled resonant frequencies.

According to one embodiment where the vibration pattern is the resonantfrequency, the method comprises the step of scanning the vibrationresponse measured for each vibration frequency of the measured spectrumof frequencies. In one embodiment, the method comprises the step ofdetermining at least one resonant frequency of reference for which thevibration response is relevantly higher than for the other frequencies.According to one embodiment, the received data is a spectrum offrequency.

In one embodiment, the step of calculating the at least one resonantfrequency value of the medium, comprises steps of: from the measurementsmade by the vibration sensor, scanning for each frequency the vibrationresponse of the medium; identifying at least one peak of the vibrationresponse; optionally recording the frequency value of the center of theat least one peak; and optionally labelling the frequency value as theresonant frequency value.

According to another embodiment, another vibration pattern can be usedto achieve the same purpose. The vibration pattern can be a feature ofthe frequency spectrum. The vibration pattern can also be the amplitudeof the signal at one predetermined frequency or the measured spectrum offrequencies.

According to one embodiment, the medical monitoring device monitors theat least one resonant frequency value to obtain information about thebone fusion process between the two separated bone sections.

In another embodiment, the vibration pattern is the vibration responsemeasured at a predetermined number of frequencies. For example, thevibration pattern can be the vibration response of the medium atsensibly 2000, 2500, 3000, 4000 and/or 4500 Hz. According to oneembodiment, the vibration pattern is the amplitude of the signal at atleast one predetermined frequency.

According to one embodiment, the vibration pattern is the amplitude ofthe signal at a predetermined frequency. According to one embodiment,the vibration pattern is a mathematical transform of the vibrationresponse such as a Fourier transform or a wavelet transform. Accordingto one embodiment, the vibration pattern is a variation of the frequencyduring the time.

According to one embodiment, this invention includes means forcalculating a modal damping factor (MDF). Advantageously, in thisinvention, the frequency spectrum is used to calculate a damping factorwhich is proportional to the width of the resonant peak about the peak'scenter frequency.

In one embodiment, the steps carried out by the calculator areiteratively carried out. In one embodiment, the steps carried out by thecalculator are carried out in a closed loop method. In one embodiment,the calculator semi-continuously executes these steps tosemi-continuously generate a distraction indicator. In one embodiment,the calculator continuously executes these steps to continuouslygenerate a distraction indicator.

According to the present invention, the calculator comprises at leastone vibration pattern of reference. According to one embodiment, themedical device comprises a memory unit comprising at least one vibrationpattern of reference.

The computer-readable data carrier determines or calculates at least onevibration pattern of the medium comprising the implantable bonedistraction device and the separated bone sections and compares thevibration pattern with a vibration pattern of reference. From thecomparison, the computer comprising the computer-readable data carrieris able to determine if the gap between the two bone sections should beincreased or not and optionally, to transmit to the actuator, a commandto increase this gap.

According to one embodiment, the medical monitoring device is configuredto be placed outside the body of the user. According to one embodiment,the medical monitoring device is a belt, preferably an abdominal belt.

In one embodiment, numerical or analogical amplifiers or filters may beused in order to treat the vibration signals before extracting avibration pattern. A correlation method, for instance using maximumlikelihood criteria, may be applied with some predefined signals havingsome predefined patterns in order to extract some vibration patterns ofthe measured signal.

From the measurement of the vibration response, a computer connected tothe computer-readable data carrier is able to calculate the at least onevibration pattern of the medium and any other suitable information fromthe recorded data.

A third aspect of the present invention relates to a medical systemcomprising an implantable bone distraction device 1 according to thefirst aspect of the present invention and a medical monitoring deviceaccording to the second aspect of the present invention. In oneembodiment, the medical device comprises an interface which activatesthe transmission of vibration data from the implantable bone distractiondevice 1 to be received by the medical monitoring device.

In one embodiment, the medical system comprises communication means toconnect the implantable bone distraction device 1 and the medicalmonitoring device. In one embodiment, the communication means compriseswireless transmission means. The transmission means may comprise atleast one transmitter and at least one receiver. In one embodiment, theimplantable bone distraction device 1 and the medical monitoring deviceboth comprise means for transmitting the measurements. In oneembodiment, the medical system comprises means for transmitting themeasurements and the means allow a bi-directional communication betweenthe medical monitoring device and the implantable bone distractiondevice 1, or between the medical monitoring device and the vibrationsensor 6.

Data collected by the at least one vibration sensor 6 are thentransmitted to the medical monitoring device. The medical monitoringdevice is then able to process these data as explained below in order togenerate a distraction indicator when the evolution of the vibrationpattern exceeds a predefined threshold.

According to one embodiment, the medical monitoring device comprisesmeans to provide energy. According to one embodiment, the medicalmonitoring device can provide the energy to be supplied to theimplantable bone distraction device 1. According to one embodiment, themedical monitoring device comprises wireless power transferring means tosupply energy to the implantable bone distraction device 1. According toone embodiment, the medical monitoring device comprises a wirelesstransmitter connected to a power source.

According to one embodiment, the implantable bone distraction device 1comprises at least one receiver. According to another embodiment, themedical system comprises a receiver connected with wire to theimplantable bone distraction device. According to one embodiment, thewireless transmitter connected to a power source conveys the fieldenergy across an intervening space to the receiver, and the receiverconverts back the field energy to an electrical current.

In one embodiment, the medical system is able to provide energy to thewireless interface for transmitting measurements and/or to the vibrationsensor and optionally to the drive rod actuator.

In one preferred embodiment, the implantable bone distraction devicecomprises at least a receiver for receiving energy and at least onetransmitter for sending the measurement data to the medical monitoringdevice. According to the embodiment, the receiver is electricallyconnected to the means for transmitting data and to the drive rodactuator.

According to one embodiment, which is not illustrated, the implantablebone distraction device is connected to the receiver for receivingenergy and connected to the at least one transmitter for sending themeasurement data to the medical monitoring device by a wire.

According to a fourth aspect, the present invention relates to a medicaldevice for distracting osteotomically separated bone sections,comprising an implantable bone distraction device 1 according to thefirst aspect of the present invention and a computer-readable datacarrier. In one embodiment, the medical device further comprises meansfor transmitting the measurements from the implantable bone distractiondevice 1 to the computer-readable data carrier. In one embodiment, thecomputer-readable data carrier comprises: at least one threshold value;and instructions which, when executed by a computer, cause the computerto carry out the steps of: a) determining at least one first vibrationpattern of the medium from the measured vibration response; and b)overtime, determining at least one second vibration pattern of themedium from the measured vibration response; c) calculating a differencebetween the at least one first vibration pattern and the at least onesecond vibration pattern; and d) generating a distraction indicator whenthe value of the calculated difference exceeds the at least onethreshold value.

In one embodiment, if the calculated difference does not exceed the atleast one threshold value, the computer carries out come-back to thestep b).

In one embodiment, the steps a), b), c) and d) are iteratively executed.

In one embodiment, if the calculated difference exceeds the at least onethreshold value, the instructions further comprise a step ofautomatically and remotely activating the actuator.

In one embodiment, the computer-readable data carrier further comprisesinstructions of automatically activating the actuator or the drive rodactuator 4 when a distraction indicator is generated.

In one embodiment, the device comprises means for distracting. In oneembodiment, means for distracting provide a distraction between the twoseparated bone sections.

In one embodiment, the distraction is actuated on the base of themeasured vibration response.

In one embodiment, the means for distracting comprise a transmitter totransmit a measured vibration response to the actuator. In oneembodiment, when the calculator of the medical monitoring devicegenerates a distraction indicator, the transmitter sends a signal to theactuator. In one embodiment, the transmitter remotely activates theactuator providing a distraction of the separated bone sections.

In one embodiment, the drive rod actuator 4 is automatically activatedwhen a distraction indicator is generated.

In one embodiment, the remote activation of the drive rod actuator leadsto adjust the space between two separated bone sections by increasing orreducing the space of a predetermined pitch.

According to a fifth aspect, the present invention relates to a method.According to one embodiment, the method is a monitoring method. In oneembodiment, the method comprises steps of: receiving data from animplantable bone distraction device 1, corresponding to a mechanicalvibration response of a medium; computing from the received data adistraction indicator by: determining at least one vibration pattern ofthe medium from the measured vibration response; analyzing the evolutionof a first value of the at least one vibration pattern from thevibration response measured during a first period; and generating adistraction indicator when the first value exceeds a predefinedthreshold.

In one embodiment, the method is a closed loop method. In oneembodiment, the present method comprises iteratively the steps ofreceiving and computing. In one embodiment, the method semi-continuouslyexecutes these steps to semi-continuously generate a distractionindicator. In one embodiment, the method continuously executes thesesteps to continuously generate a distraction indicator.

In one embodiment, the method further comprises the step of activatingthe actuator when a distraction indicator is generated.

In one embodiment, the method is an opened loop method.

The present invention further relates to an operating method comprisingthe monitoring method according to the present invention and a step ofadjusting the space between two separated bone sections by increasing orreducing the space of a predetermined pitch when the distractionindicator is generated.

In one embodiment, a predetermined pitch is a distance which could beapplied to move apart two separated bone sections without breaking thecallus between the two separated bone sections. In one embodiment, thepitch is ranging from 0.1 to 5 mm.

In one embodiment, the method uses the medical system according to thethird aspect of the present invention.

In the descriptions above and in the claims, phrases such as “at leastone of” or “one or more of” may occur followed by a conjunctive list ofelements or features. The term “and/or” may also occur in a list of twoor more elements or features. Unless otherwise implicitly or explicitlycontradicted by the context in which it is used, such a phrase isintended to mean any of the listed elements or features individually orany of the recited elements or features in combination with any of theother recited elements or features. For example, the phrases “at leastone of A and B;” “one or more of A and B;” and “A and/or B” are eachintended to mean “A alone, B alone, or A and B together.” A similarinterpretation is also intended for lists including three or more items.For example, the phrases “at least one of A, B, and C;” “one or more ofA, B, and C;” and “A, B, and/or C” are each intended to mean “A alone, Balone, C alone, A and B together, A and C together, B and C together, orA and B and C together.” Use of the term “based on,” above and in theclaims is intended to mean, “based at least in part on,” such that anunrecited feature or element is also permissible.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of the disclosure.As used herein, the terms “first,” “second,” and the like, do not denoteany order, quantity, or importance, but rather are used to distinguishone element from another, and the terms “a” and “an” herein do notdenote a limitation of quantity, but rather denote the presence of atleast one of the referenced item. It will be further understood that theterms “comprises” and/or “comprising,” when used in this specification,specify the presence of stated features, integers, steps, operations,elements, and/or components, but do not preclude the presence oraddition of one or more other features, integers, steps, operations,elements, components, and/or groups. As used herein, “substantially”refers to largely, for the most part, entirely specified or any slightdeviation which provides the same technical benefits of the disclosure.

The implementations set forth in the foregoing description do notrepresent all implementations consistent with the subject matterdescribed herein. Instead, they are merely some examples consistent withaspects related to the described subject matter. Although a fewvariations have been described in detail herein, other modifications oradditions are possible. In particular, further features and/orvariations can be provided in addition to those set forth herein. Forexample, the implementations described above can be directed to variouscombinations and sub-combinations of the disclosed features and/orcombinations and sub-combinations of one or more features further tothose disclosed herein. In addition, the logic flows depicted in theaccompanying figures and/or described herein do not necessarily requirethe particular order shown, or sequential order, to achieve desirableresults. The scope of the following claims may include otherimplementations or embodiments.

We claim:
 1. A monitoring method for generating a distraction indicator,comprising: receiving data from an implantable bone distraction device,corresponding to a mechanical vibration response of a medium comprisingthe implantable bone distraction device, as measured by at least onevibration sensor; computing from the received data a distractionindicator through at least the steps of: determining at least onevibration pattern of said medium from the vibration response measured bythe at least one vibration sensor; analyzing the evolution of a firstvalue of the at least one vibration pattern of said medium determinedfrom the measured vibration response during a first period; andgenerating a distraction indicator as a function of the first value. 2.The method of claim 1, wherein computing the distraction indicator fromthe received data comprises: determining at least one vibration patternof said medium from the vibration response measured by the at least onevibration sensor; analyzing the evolution of a first value of the atleast one vibration pattern of said medium determined from the measuredvibration response during a first period; analyzing the evolution of asecond value of the at least one vibration pattern of said mediumdetermined from the measured vibration response during a second period;performing a comparison between the first value and the second value;and generating a distraction indicator as a function of said comparison.3. The method of claim 2, wherein generating the distraction indicatoris performed when a comparison between the first value and the secondvalue exceeds a predefined threshold.
 4. The method of claim 3, whereinthe predefined threshold ranges from approximately 1 percent toapproximately 7 percent of the first value.
 5. The method of claim 3,wherein the predefined threshold ranges from approximately 0.5 percentto approximately 10 percent of the first value.
 6. The method of claim3, wherein the predefined threshold ranges from approximately 0.5percent to approximately 20 percent of the first value.
 7. The method ofclaim 1, wherein the at least one vibration sensor is implanted in apatient.
 8. The method of claim 1, further comprising calculating adistraction indicator from the received vibration data as a function ofan evolution of the vibration data over time, wherein the evolution ofthe vibration data is an indicator of callus formation between the firstbone section and the second bone section.
 9. The method of claim 1,further comprising transmitting instructions to the implantable bonedistraction device for providing a distraction when the distractionindicator is generated.
 10. The method of claim 1, further comprisingadjusting a space between two separated bone sections by increasing thespace when the distraction indicator is generated.
 11. The method ofclaim 1, further comprising adjusting a space between two separated bonesections by reducing the space when the distraction indicator isgenerated.
 12. The method of claim 1, wherein the implantable bonedistraction device is configured to measure a vibration response of themedium at a frequency range of from approximately 20 Hertz (Hz) toapproximately 10,000 Hz.
 13. The method of claim 12, wherein theimplantable bone distraction device is configured to measure a vibrationresponse of the medium at a frequency range of from approximately 30 Hzto approximately 7,000 Hz.
 14. The method of claim 13, wherein theimplantable bone distraction device is configured to measure a vibrationresponse of the medium at a frequency range of from approximately 40 Hzto approximately 5,000 Hz.
 15. The method of claim 1, whereindetermining the at least one vibration pattern of the medium isperformed continuously or semi-continuously.
 16. The method of claim 15,wherein when the first value of the vibration pattern is determined, thefirst value becomes the reference.